Tuberculosis (TB) is the second-leading cause of death by infection. Novel strategies are critically needed to shorten treatment duration and treat multidrug resistant (MDR) and extensively drug-resistant (XDR) TB. The applicant is pursuing joint training in Clinical Pharmacology and Infectious Diseases and will combine her expertise in these areas to lead the rational development of new treatments for TB. The K23 award would provide the ideal vehicle for her to complete her education and training so she may launch an independent career in academic clinical research focused on TB therapeutics. The overall goal of this proposal is to evaluate pharmacokinetic and pharmacodynamic (PK/PD) parameters of two promising new TB treatments. First, moxifloxacin- and rifapentine- (RPT) containing regimens are strikingly effective in mice. Defining the PK/PD parameters that predict treatment response in humans will be essential for developing rational dosing regimens. Rifamycin hypersensitivity, however, may occur with high-dose, intermittent RPT and impact its safety. Second, TMC207 is a new agent being developed for TB treatment that is active against MDR TB. It is metabolized by the cytochrome P450 isoenzyme 3A4 (CYP3A4), so drug interactions with agents used to treat human immunodeficiency virus (HIV) are likely. We propose: AIM 1: To identify, for RPT and moxifloxacin, the PK/PD parameters that correlate most strongly with treatment response. We will perform a PK study nested in a Phase II randomized trial comparing a moxifloxacin- and RPT-based regimen to standard therapy during intensive phase TB treatment in Brazil. AIM 2: To investigate the incidence and immunopathogenesis of rifamycin hypersensitivity syndrome in patients receiving high-dose, intermittent RPT in the context of the Phase II trial. AIM 3: To determine the impact of antiviral drugs (ARVs), beginning with efavirenz (EFV), on the steady state pharmacokinetics of TMC207 in healthy volunteers. These studies will be performed at Johns Hopkins University with AIDS Clinical Trials Group (ACTG) support. Through these studies, we will better understand the pharmacology of moxifloxacin- and RPT-based regimens, allowing for optimization of this potent new regimen which may shorten TB treatment. This work will also provide crucial information that will impact the treatment of TB/HIV coinfected patients worldwide.